What is the 15 second rule block timestamp?
Could you please elaborate on the concept of the "15 second rule block timestamp" in the world of cryptocurrency? Is it a standardized practice among blockchains, or is it specific to certain networks? How does it play a role in ensuring the security and integrity of transactions? And what happens if a block is not mined within this 15-second timeframe? Understanding this rule will greatly aid in comprehending the intricacies of blockchain technology.